These types of tabletop cutting devices include a table on which the material to be cut (workpiece) is placed and a cutting device main body that is supported on a rear part of the table so as to be movable along an up-to-down direction. The cutting device main body includes a circular cutting blade (cutting edge) that can be rotated by an electric motor as a driving source. Cutting work can be performed by moving the cutting main body in a downward direction, causing the rotating cutting blade to cut the workpiece placed on the table.
In these types of the tabletop cutting devices, the table is supported on a base so as to be horizontally rotatable. By rotating the table, a cutting angle of the cutting blade with respect to the workpiece can be arbitrarily changed in order to perform a so-called oblique cutting.
A rotation position of the table can be fixed by a rotation lock mechanism (miter lock mechanism). The rotation lock mechanism includes a so-called positive-lock-type lock mechanism and a free-lock-type lock mechanism. In the positive-lock-type lock mechanism, the table can be locked at one of predetermined angle positions by inserting a lock pin etc. into one of lock holes that are provided on the base side at every fixed angle. In the free-lock-type mechanism, the table can be locked at an arbitrary angle position, at which the table cannot be locked in the former positive-lock-type lock mechanism, by pressing the lock pin etc. to the base side by a screw force or a spring force. Prior arts relating to the latter rotation lock mechanism, i.e., the free-lock-type mechanism, are disclosed in the following Japanese Patent Publications.
Japanese Laid-Open Patent Publication No. H05-318402 (patent document 1) discloses a configuration in which a rotation position of the table can be locked by directly pressing a tip end of a screw shaft to a wall portion provided on the base. Japanese Laid-Open Patent Publication No. H09-131701 (patent document 2) discloses a configuration in which a rotation position of the table can be locked by pressing a tip end of a screw shaft to the base side via a swing lock member. Japanese Laid-Open Patent Publication No. 2002-200602 (patent document 3) discloses a configuration in which a rotation position of the table can be locked by pressing a lock member to the base side with a spring force. Furthermore, Japanese Laid-Open Patent Publication No. 2010-58229 (patent document 4) discloses a configuration in which a rotation position of the table can be locked by holding a lock plate provided on the base side with a spring force.
With regard to the latter free-lock-type rotation lock mechanism, operability needs to be improved. As to an operation by which a rotation position of the table is locked at an arbitrary angle position, many users prefer, in terms of ease of use, an operation in which an operation portion is rotated to apply a screw force. Because of this user's preference, the configuration in which the rotation position of the table is locked by applying the spring force (patent document 4) has been producing a problem of impairing user's operation comfort.
Furthermore, in the configuration in which the rotation position of the table is achieved by applying the screw force (patent documents 1-3), friction and/or deflection may cause large transmission loss of the operation force and thus careful operation has been needed to obtain an adequate fixing force. In the prior art, operability has been impaired in this respect.